Many professional athletes, but also joggers or persons performing other physical exercises use pulse watches as a training aid today. The pulse watches may also incorporate positioning systems for collecting more sophisticated information during exercise. However, the pulse watches still provide a limited amount of information, and does not provide any information about how a physical exercise or movement is performed. Different tools based on video analysis are used in many sports for post hoc analysis of movements and physical exercises. Such tools may comprise everything from simple systems based on consumer cameras with graphic annotation interfaces, to considerably more complex and expensive motion-capture systems for more precise three dimensional modeling of movements. A drawback of such tools is that the feedback is provided only after the exercise, and that it may be difficult to observe small differences between movements performed by the athlete. Furthermore, the tools based on video analysis are difficult to use in a sport such as cross-country skiing or running, as the athlete is moving over a large area during the exercise, and it may be difficult to capture every movement with a camera.
Another type of tools for analysis of an athlete's movements is based on the use of sensors placed on different parts of the athlete's body, where the sensors typically communicate wirelessly with a computer. The sensors may capture data which may be difficult for a trainer to see with his own eyes. The computer may thus capture data from the sensors on the athlete's body during the exercise, and the captured data may then be used in an analysis tool on the computer to analyze the athlete's performance and movements. The analysis can be used e.g. as a training aid to improve the performance of the athlete. However, a great number of sensors may be needed to get a useful result, and they may interfere with the athlete's movements during the exercise. Furthermore, even if the data capture is performed during the exercise, it may still be complex and time consuming to analyze the large amount of data that is collected and to provide relevant and understandable feedback in real-time during the exercise.